1. Field of the Invention
Industrially prepared perfume oils nowadays consist for the greatest part of synthetic fragrances.
2. Description of the Related Art
Although the traditional use of essential oils and extracts of a vegetable and animal origin continues to play an important role in the field of alcoholic (fine) perfumery, the perfuming of laundry detergents, soaps, household cleaners and similar technical products requires the use of fragrances which satisfy the technical requirements with regard to stability and substantivity. In order to correspond with these particular requirements, perfumes for use in technical consumer goods are largely formulated from synthetic fragrances. However, because these perfumes are needed in large amounts, all of the important perfume houses and fragrance manufacturers of aroma substances have in the last few decades directed their research activities to the preparation of novel synthetic fragrances.
In the meantime, synthetically prepared fragrances which in the past have been prepared essentially for technical use because of their comparatively low price and their high stability, have increasingly been used in fine perfumery as well.
Meanwhile there is a constant need for fragrances with improved properties, such as odor quality, stability, skin compatibility and environmental compatibility. For the purposes of a good ecobalance, products are strived for here which are based on renewable raw materials.
One raw material of natural origin which is available in relatively large amounts is the sesquiterpene longifolene (1), which occurs as the main component in Indian turpentine oil and as a secondary component in numerous other types of turpentine oil and other essential oils. Even more than 2 decades ago a number of secondary products from longifolene had been prepared and the fragrance properties thereof described. G. Ohloff reports in his book xe2x80x9cRiechstoffe und Geruchssinnxe2x80x9d [Fragrances and Sense of Smell] [Springer-Verlag, 1990, ISBN No. 3-540-52560-2, pages 87-88] in summary that at least 4 commercial fragrances are derived from (+)-longifolene (1), and 13 fragrance derivatives can be commercially utilized from the isolongifolene (2) accessible therefrom by isomerization. Some of these derivatives are given the characteristic odor type woody (odor of wood) by Ohloff; other odor notes are not mentioned.
The chemistry and odor properties of the commercially important derivatives of isolongifolene (2) have been reported by G. Fxc3xa4rber and H. Tan [G. Fxc3xa4rber, Parfxc3xcmerie+Kosmetik, 68, 18 (1987), H. Tan, Parfxc3xcmerie+Kosmetik, 67, 564 (1986)]. In this connection, the last-named publication in particular reveals that the isolongifolene derivatives known as fragrance can be used instead of the known wood scent note because of their woody character.
Our publication EP-A 0 543 470 describes cyclic isolongifolanone ketals of the general formula B 
(in which wavy lines are xcex1- and xcex2-configuration, and R and Rxe2x80x2 are hydrogen or methyl or ethyl radicals). These ketals are valuable fragrances which have strong woody odor properties with floral-fresh effects and velvety moss/ambergris character.
Our publication EP-A 0 669 308 describes isolongifolanole derivatives of the general formula C 
(in which wavy lines are xcex1- and xcex2-configuration, and R1 is hydrogen or methyl radicals and R2 is methyl or ethyl radicals). These derivatives likewise have woody olfactory properties.
GB-A 1 505 821 describes isolongifolanole and lower esters thereof (acyl groups with up to 6 carbon atoms) as fragrances, the xcex1-/xcex2-isometry of the hydroxyl or carboxyl function being discussed. Said fragrances have strong woody odor properties reminiscent of cedryl acetate and vetiveryl acetate and are particularly highly suitable for perfume compositions with floral or citrus-woody character.
GB-A 1 256 535 describes the controlled oxidation of isolongifolene (2) to isolongifolenone (3) and subsequent reduction thereof to isolongifolenol (4). The subsequent esterification (acyl groups having up to 5 carbon atoms) of the virtually odorless isolongifolenol (4) again leads to fragrances (isolongifolenyl esters) with a woody odor profile.
According to the prior art just given, the field of longifolene and isolongifolene derivatives appears to have been investigated particularly thoroughly. In addition to a limited number of longifolene and isolongifolene derivatives with valuable fragrance properties (cf. in particular the abovementioned prior art), there is an utterly confusingly large number of derivatives of the abovementioned sesquiterpenes described in the literature or synthesized and investigated by ourselves which are of little or no significant olfactory value.
Even if some of the known isolongifolene derivatives have excellent olfactory properties and can be prepared on an industrial scale in a manner which is both low in cost and also environmentally compatible, it would nevertheless, looking at the group of isolongifolene derivatives as a whole, increasingly be perceived as disadvantageous and restrictive that for isolongifolenol derivatives with a noteworthy olfactory activity, a woody aspect frequently is in the foreground, which limits the use spectrum of the derivatives.
It was therefore the primary object of the present invention to provide a fragrance, preferably an isolongifolene derivative or a group of isolongifolene derivatives, and a process for the preparation thereof, where, compared with the isolongifolene derivatives of olfactory interest mentioned before, at least not only the woody, but also other odor aspects should be in the foreground. Advantageously, the nonwoody aspects should be dominant here.
In connection with this, a further object was to provide a perfume composition whose olfactory properties are codetermined by a fragrance, preferably an isolongifolene derivative or a mixture of isolongifolene derivatives, for which at least not only woody but also other odor aspects are in the foreground.
Further objects on which the present invention is based can be formulated as follows: The isolongifolene derivative or the mixture of isolongifolene derivatives should as far as possible be able to contribute to a long-lasting after-odor and to a good fixing of a perfume composition.
The isolongifolene derivative or the mixture of isolongifolene derivatives should as far as possible be able to contribute in a perfume composition to a rounding off and harmonizing of the main note (the xe2x80x9cbouquetxe2x80x9d).
Finally, a further object of the present invention was to provide a process with which a material (a substance) can have added to it a (not primarily woody) odor or have its (intrinsic) odor intensified, by adding an isolongifolene derivative or a mixture of isolongifolene derivatives to the material (the substance).
Finally, a further object of the present invention was to provide a process with which a material (a substance) can have added to it a (not primarily woody) odor or have its (intrinsic) odor intensified, by adding an isolongifolene derivative or a mixture of isolongifolene derivatives to the material (the substance).
There is particularly great interest in this connection in fragrances with a musk character. The isolongifolene derivatives used hitherto as fragrances do not usually have a musk character of this type. To prepare perfume oils with a musk note, it is therefore necessary to mix one of the known musk fragrances with the respective isolongifolene derivative.
Thus, for example, the already mentioned GB-A 1 256 535, inter alia, recommends mixing the isolongifolenol esters described therein with a musk compound, such as musk ketone or ethylene brassylate.
In the likewise already mentioned GB-A 1 505 821, musk compounds are likewise among the preferred compounds for mixing with the disclosed isolongifolene derivatives.
The situation is similar also with regard to the compounds disclosed in our own specified publications.
According to the invention, the proposed object is achieved by the provision and use of the novel compound of the general formula A 
(in which wavy lines are xcex1- and xcex2-configuration, and R=methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl-, iso-butyl, tert-butyl radicals).
The individual compounds covered by this general formula, and mixtures thereof (i.e. enantiomer mixtures and/or mixtures of pure or mixed enantiomers having different radicals R) have quite unique odor properties and also differ markedly from the known fragrances from the family of isolongifolenol derivatives discussed above. For example, the novel individual compounds covered by general formula A interestingly have only very weak woody odor properties. Instead, they are characterized by a strong, smooth, velvety musk/ambergris odor; in some cases, a patchouli aspect can also be established in the after-odor. The above odor characteristics apply in particular to (individual) compounds of the general formula A where R=methyl, ethyl, propyl, and iso-propyl (in each case pure enantiomer or enantiomer mixture). For mixtures of said individual compounds with a different alkyl radical in the ether function, corresponding statements apply.
Furthermore, in perfume compositions with a floral accent, the individual compounds covered by general formula A, and mixtures thereof, intensify in a synergistic manner the floral effect and refresh this effect, in particular in the top note.
The individual compounds (pure enantiomers or enantiomer mixtures) according to the invention covered by the general formula A are particularly long-lasting and fixing.
Cyclic isolongifolenyl ethers of the general formula A where R=Me, Et, Pr or iso-Pr, in which the configuration of the ether function is xcex1 or xcex2 or the cyclic isolongifolenyl ether comprises a mixture of enantiomers which differ in the configuration of the ether function are, however, preferred in this respect over the ethers (pure enantiomer or enantiomer mixture) of the general formula A where R=butyl, sec-butyl, iso-butyl or tert-butyl.
Of these, particular preference is in turn given to the isomer ethers of the general formula A where R=methyl (pure enantiomer or enantiomer mixture) because of
(a) their particular odor characteristics (with musk aspects) which influence in particular the after-odor of a perfume composition,
(b) their high fixing ability and their good adhesion to customary substrates,
(c) their ability to be used for intensifying in particular floral top notes and
(d) their ability to be used for rounding off and harmonizing certain main notes for use in perfumery.
The isomeric ethers of the general formula A where R=ethyl, propyl or iso-propyl (pure enantiomer or enantiomer mixture) likewise have surprisingly marked odor characteristics which influence the after-odor of a perfume composition, but are overall not quite so odor-intensive as the isomers of the general formula A where R=methyl. They are therefore intended in particular for the rounding off and harmonizing of certain main notes.
To prepare the methyl ethers covered by the general formula A, (+)-longifolene (1) was, isomerized according to the process diagram in FIG. 1 in a known manner by treatment with a mixture of acetic acid and sulfuric acid (U. R. Nayak S. Dev, Tetrahedron 8, 42-48 (1960)) or with boron trifluoride etherate (R. E. Beyler, G. Ourisson, J. Org. Chem., 30, 2838-2839 (1965)) to give isolongifolene (2). Subsequent controlled
(a) oxidation of isolongifolene (2) with sodium bichromate in glacial acetic acid (DE 1804711) or
(b) air oxidation of isolongifolene (2) (Organikum 16, 169-170 (1986)) (G. Fxc3xa4rber xe2x80x9cRiechstoffe aus Isolongifolenxe2x80x9d (Fragrances from Isolongifolene), Parfxc3xcmerie+Kosmetik, 68, 18 (1987))
led to isolongifolenone (3).
Isolongifolenone (3) was then reduced in a manner known per se to give a mixture of the epimer alcohols 4a and 4b, the mass ratio of 4a:4b depending on the reaction conditions chosen. The chiral alcohols 4a/b were converted as a mixture or in pure form in a manner known per se into the epimeric methyl ethers 5a and 5b.
The preparation of the epimeric ethyl, propyl, iso-propyl, butyl, sec-butyl, isobutyl and tert-butyl ethers (compounds 6a/b-12a/b) was carried out in an analogous manner (cf. the preparation procedures below).
The stereochemical ratios remain essentially unchanged during the reaction of the isolongifolenol epimer mixture 4a/b or of the pure epimers 4a or 4b to give the novel ethers of the general formula A, meaning that the novel ethers of the general formula A were also present depending on the stereochemical composition of the isolongifolenol as epimer mixtures or pure epimers. With regard to the isolongifolenol epimer mixtures 4a/b, it must also be taken into consideration that the epimeric alcohols 4a and 4b can form in varying amounts depending on the reaction conditions chosen during the reduction of the isolongifolenone (3), meaning that, following etherification, the epimeric methyl ethers 5a and 5b can likewise be present in varying quantitative ratios.
Corresponding to the above statements, starting from (+)-longifolene (1) via the chiral isolongifolenols 4a/b, the corresponding likewise chiral ethers of the general formula A were obtained. (+)-Longifolene (1) is, because of its low-cost availability, currently and must also in the future be the preferred starting compound for the preparation of isolongifolenol derivatives in industrial practice. When this starting compound is used, the stereochemistry of the corresponding isolongifolenyl ethers according to the invention is fixed with the exception of the carbon carrying the ether function. The hydrogen on the bridgehead of the five-membered rings is xcex1-configured.
Starting from the epimeric (xe2x88x92)-longifolene present in Pinus ponderosa, the corresponding isolongifolenyl ethers which are stereochemically different from the compounds 5a/b-12a/b were also synthesized in an analogous manner. These do not differ significantly in their properties from the ethers which were obtained starting from (+)-longifolene (1). In FIG. 1 and the text below, the invention is therefore only illustrated for the sake of clarity with reference to the compounds based on (+)-longifolene (1). For the compounds obtainable starting from (xe2x88x92)-longifolene, the corresponding statement applies in each case.
In a process for the preparation of a cyclic isolongifolenyl ether according to the invention, isolongifolenol is therefore reacted in enantiomerically pure form or as an enantiomer mixture either under acid-catalyzed conditions with an aliphatic alcohol (alkyl hydroxide) or under base-catalyzed conditions with an alkyl halide or alkyl sulfate in an aprotic solvent, the respective alkyl function corresponding to the radical R of the cyclic isolongifolenyl ether of the general formula A.
The novel ethers of the formula A have in each case in pure form or as stereoisomer mixtures original fragrance properties and can advantageously be used in pure form or as isomeric mixtures as fragrances or constituent of perfume oils.